Artificial foot with ankle-joint



1386- 1952 G. GREISSINGER ARTIFICIAL FOOT WITH ANKLE-JOINT Filed Sept. 24, 1949 Patented Dec. 9, 1952 ARTIFICIAL FOOT WITH ANKLE-JOINT Georg Greissinger, Stuttgart-Vaihingen, Germany Application September 24, 1949, Serial N 0. 117,681 In France September 27, 1948 3 Claims.

The invention relates to an artificial foot with an ankle-joint which, on the foot part and on the shank part, is provided with cooperating generating surfaces. Such an artificial foot is known and has proved its value. In the known embodiment two generating bodies are provided which are screwed to the foot part and to the shank part. Both of the generating bodies are connected laterally by means of links, while foot part and shank part are held together by means of a spring supported tie-bolt link-supported to the latter.

In contradistinction thereto, the subject of the invention is distinguished by the feature that the ankle-joint has joint parts which are installed rigidly within the foot part and shank part, and that at least one of the generating surfaces appertains to a generating body which is of elastic material, for example, rubber. The same is preferably inserted merely between foot part and shank part, for example, into a recess of one part and the other generating surface is to be provided for directly on the other part. This new conformation signifies a remarkable structural simplification.

The invention further provides for the development of the ankle-joint to be universally movable, for example, as a ball-and-socket joint or as a universal joint. By this means, an anklejoint is obtained which is movable in every direction as is extant in the human foot, and of geratimportance for unimpaired walking on any kind of surface. I

The generating body of elastic material, whose outline may be circular, oval or rectangular, is preferably developed so that it will have the greatest yieldability on the side facing the heel. The objective is that when turning the joint towards the front the resistance is greater than when turning it towards the rear, corresponding to the natural ankle joint.

An artificial foot, with a universally movable ankle-joint, in which both parts are held together by a universal joint, is in itself known. However, in this instance, the matter in question is an artificial foot with an intermediate rubber part which is, when moving the foot part with respect to the shank part, merely deformed, and does not constitute a generating body.

In the drawing an embodiment of the subject'of the invention is illustrated in 5 figures, it is shown Fig. 1, a longitudinal section of the artificial foot,

Fig. 2, a top view upon the foot part,

2 Fig. 3, a section taken on the line AB of Fig.1,

Fig. 4, a longitudinal section of the elastic generating body in somewhat enlarged scale, and

Fig. 5, a top view of the same.

The foot part is designated by a, and the shank part by b. The lower part and the fore part of the foot may be formed in a conventional manner (see Figs. l-3).by a yielding foundation c, for example, of felt. Foot part a and shank part b are linked to each other. The joint is universally movable and is developed as a ball-andsocket joint. The one part (1 of the joint having the form of a bushing is inserted into a recess provided in the bottom of the shank part b. With its threaded extension e it penetrates the bottom of the shank part b and by means of a nut f it is screwed tightly to the latter. The recess in the shank part is reinforced on its bottom part by a metal plate 72. in which a, protection against torsion is effected by an oblong shoulder g. The other joint part i is a ball which is provided with a slot it open at the top, through which a pin Z extends which is supported in the joint part 11 transverse to the longitudinal direction of the foot. By this, the ball is insured against torsion about the axis of the shank part b. A threaded bushing m, screwed into the hollow space of the joint part d, is developed as a socket for the ball 1'. To fasten the ball 2' on the foot part a the former has a threaded extension n penetrating the latter, and a nut q is screwed on this extension in a recess of the foot part a. The threaded extension n bearing the ball z is secured against torsion by an oblong shoulder o in a metal plate p fastened to the foot part a.

On the upper face of the foot part a, within the range of the joint, a recess is provided into which, an annular generating body T which, for instance, is of rubber, is inserted. The shank part b is supported upon this generating body, whose outline as shown in Figs. 2 and 5, is preferably oval, but it may also be circular or rectangular, The supporting surface of the shank part is developed as a curved generating surface. The front part 3 of the generating surface is curved less than the rear part t (see esp. Fig.4). The generating surfaces 1), uof the elastic body 1* lie in the same plane. The rear part of the surface, as is indicated by dash and dot lines 10, may also slope somewhat. Owing to the oval form of the generating body r, as perceived from Figs. 2 and 5, and to the recess for the joint parts being displaced out of the center towards the rear, the front supporting surface 11 is large, wherea the rear supporting surface it is merely a small semiannular surface. This has the result that the elastic generatin body presents its greatest yieldability on the rear part facing the heel. Consequently, when turning the joint towards the front, the resistance is greater than when turning it towards the rear which is also the case with the human foot; Also, this "effect is assisted by the fact that the rear part if of the generating surface on the shank part b is curved more than the front part s.

Because of the ball-and-socket joint, the foot part a, with respect to the shank part b permits universal movement. During all these movements a mutual generating motion of the surfaces 12, s, respectively u, 73 takes place which is attained by an elastic yielding of the elastic material of' the generating body, according to the advance or recession of the parts a and b. Turning motions of the foot transverse to the longitudinal direction are also possible; they are limited by the transverse pin Z to an extent, corresponding to that in the natural anklejoint.

A Cardan'joint may of course take the place of the ball-and-socket joint. Abandoning the lateral movability of the foot part a, a simple rule-joint would also lie within the scope of the invention.

It will beobvious that the details of constructionmay be varied from those shown in the drawing. I therefore do not limit myself to such details.

Having described my invention I claim:

1. Artificial ankle joint apparatus comprising in: combination, an artificial foot portion; an artificial limb having a lower end portion located directlyabove andin spaced relationto said foot portion; and universal joint means located between said portions and being fixedly connected thereto so that said. portions may rotate with respect to each other but may not move toward or away from each other; first resilient means located on the toeward side of said joint means for yieldingly resisting rotation of said artificial limb toward the toe of said artificial foot portion, said first resilient means comprising a substantially semicircular block of resilient material mounted on one of said portions and having a substantially fiat, broad outer surface confronting-and at least partially spaced from the other of said-portions; and second resilient means 10- cated'on the heelward side of said joint means. for yieldingly resisting rotationof said artificial limb toward the heel of said foot portions, said second resilient means comprising a substantially thereto so that said portion-s may rotate with respect to each other but may not move toward or. away from each other; first resilient means locatedon the toeward side of said joint means for yieldingly: resisting rotation of said artificial limb toward. theltoe of saidartificial foot por tion, said first resilient means comprising a substantially semicircular block of resilient material mounted on one of said portions and having a substantially fiat, broad outer surface confronting the other of said portions; and second resilient means located on the heelward side of said joint means for yieldingly resisting rotation of saidartificial limb towardthejheel of said foot portions, said secondresilient means comprising a substantially semicircular block of resilient material mounted on said one of said portions, being of substantially less volume than said first resilient means and having an outer surface'confronting said other portion, being of substantially less area than said outer surface of said first resilient means and being located in the'same plane as the latter, said lower end portion of said artificial limb having curved surfaces confronting said first and second resilient means and said curved surface which confronts said first resilient means-being generatedon a radius which is substantially larger than the radius on which said curved surface confronting said second resilient means is generated;

3. Artificial ankle joint apparatus comprising, in combination, an artificial foot portion formed with a recess in its uppersurface andwitha bore extending therethrouglr and communicating with a centralpa-rt of said: recess-ran artificial limb having a lower end portion locatedin overlying and spaced relation with respect to said recess, said lower end portion having a curved surface confronting said recess with the portion of the curved surface located on the toeward side of said end portion being generated on a radius-which is substantially larger than theradius on which the portion of the curved surface-located on the heelward side of saidend portion. is generated, and said end portion beingformed. with a bore extending therethrough; ball and socket joint means located between said foot portion and end portion, saidball being integral with a shaft extending through said bore in said foot portion and fixedly mounted against movement therein, saidsocket being integral with a shaft extending through said bore in said end portion and being fixedly mounted against movement therein, whereby the limb is prevented from moving as a unit toward and said ball and socketto rotate slightly about the longitudinal axis of said artificial limbas in a natural ankle joint; a substantially oval blockof resilient material mounted in said recess in said foot portion and being formed with a cen-' tral substantially circular opening in which said joint means is located, said block having a broad substantially flat upper surface located on the toeward side thereof and confrontingthe portion of the curved surface located on the toeward side of said end portion so as to'c'ontact thesame during movement of said limb'to-- Wardthe toe of said foot portion and'said block having a narrow upper surface of substantially less area than said fiat upper'surface, located on the heelward side thereof and confronting said portion of the end portion curved surface located on the he'elward' side thereof so as to contact the same during rotation of the limb" toward the heel oftheifo'ot member, whereby the limb may be moved toward the heel with greater 8 UNITED STATES PATENTS Name Date Peters Jan. 9, 1900 Harrison Aug. 29, 1911 Milligan Mar. 17, 1914 Van Cise July 7, 1942 FOREIGN PATENTS Country Date Germany Apr. 27, 1911 Germany Jan. 31, 1938 

